JP4832707B2 - Discriminator detection using multiple signal combinations. - Google Patents

Description

【００３５】
【表２】

【００３６】
非常に多数の独立変数を得るための上記の特徴のいずれかを組み合わせることに加えて、特徴の幾らかは他のものの代用になり得る。例えば、回転する指向性アンテナは、同じ方向を介した通信が周期的時間に得られるのと同程度である点で指向性ダイバーシティ並びにタイミング・ダイバーシティと見なされ得る。ダイバーシティは、同時に又は順次的に実現され得る。順次的ダイバーシティの例として、タイミング・ダイバーシティは、単一送信の多重受信、又は順次的（例えば、周期的に反復される）送信−受信事象と関わり得る。
【００３７】
リンカと識別装置との間のリンクに対して、リンカ端で独立変数の値を決定する（例えば、前述したようにリンカ１１０、モニタ１０６及び／又はホスト・コンピュータ１０２による決定）目的のためのダイバーシティは、リンカか、又は識別装置かのいずれかで実行され得る。例えば、方向及び／又は偏波ダイバーシティは、追跡されるべき同じ対象物に配置された１つ又はそれより多い識別装置により達成され得る。説明の目的のため、図４の対象物４００（例えば、通常の運送箱）は、相互に直交した側面４１０、４２０及び４３０と、側面４２０及び４３０に対してそれぞれ共平面上で添付された識別装置４５０及び４５２と、２つの側面４１０及び４２０に共平面上で添付された識別装置４４０と、３つの側面４１０、４２０及び４３０に共平面上で添付された識別装置４４０とを含む。対象物４００上の識別装置は、同じ識別信号特性又は符号でもって応答し得る。
【００３８】
識別装置は、実質的に平面であり且つ指向性及び／又は偏波特性の影響下にあるタイプのアンテナを含み得る。それぞれこのタイプのアンテナを有する識別装置４５０及び４５１が、図示されるように、対象物の相互に垂直の面に取り付けられたとき方向及び／又は偏波ダイバーシティを呈するように用いられ得る。識別装置は、このタイプの２以上のアンテナを有し得る。方向及び／又は偏波ダイバーシティは、複数のアンテナ識別装置の各アンテナにより異なる向きを用いることにより得られることができる。例えば、識別装置４４０は、対象物４００の側面４１０上に配置された第１のアンテナを有する部分４４１と、対象物４００の側面４２０上に配置された第２のアンテナを有する部分４４２とを有する。更に、識別装置４４４は、対象物４００の側面４１０上に配置された第１のアンテナを有する部分４４５と、対象物４００の側面４２０上に配置された第２のアンテナを有する部分４４６と、対象物４００の側面４３０上に配置された第３のアンテナを有する部分４４７とを有する。アンテナの機能（例えば、電力の吸収、共振の検出、メッセージ受信、及び／又はメッセージ送信に対する）は、そのような識別装置（４４０又は４４４）において同一であり得て、又は異なり得る。異なるとき、アンテナの機能は、同じリンク又は異なるリンクに参加し得る。
【００３９】
本発明の様々な局面に従った識別装置は、媒体ダイバーシティ、指向性ダイバーシティ、偏波ダイバーシティ、信号タイミング・ダイバーシティ信号、変調ダイバーシティ、冗長構成要素ダイバーシティ、又はそれらの任意の組み合わせを促進し得る。例えば、図５のビーコン識別装置１６０は、バッテリ５０２、制御器５０４、及び幾つかの伝送チャネルを含む。各伝送チャネルは、送信器（５０８及び５１２）とそれぞれのアンテナ（５１０及び５１４）とを含む。バッテリ５０２は、電力を制御器及び送信器に導体５０１を介して供給する。制御器５０４は、いずれかの又は全部の送信器が送信するとき、及びどのような信号（例えば、内容、周波数（単数又は複数）及び／又は変調）をそれぞれが送信することになるかを決定する。任意の従来の部品、回路、構造、材料及び技術を用いて、識別装置１６０を製作し組み立て得る。
【００４０】
製造のための識別装置１６０の部品、回路、構造、材料及び技術は、上記で参照された米国特許出願０９／３７２，２７４に記載されているタイプを含む任意の従来のタイプで、本明細書で説明した機能を実行するため適切に適合されているものであり得る。
【００４１】
媒体ダイバーシティは、任意の１つ又はそれより多い伝送チャネルの代わりに別の媒体に対する送信器及びインターフェース（例えば、圧電型発振器及び超音波信号のための放射表面）を用いることにより実行され得る。
【００４２】
指向性ダイバーシティ及び偏波ダイバーシティは、前述したように、異なるアンテナ・パターンを備えるアンテナ５１０及び５１４を採用することにより容易に行われ得る。
【００４３】
信号変調ダイバーシティは、それぞれの送信器５０８−５１２においてそれぞれ異なる変調を採用し、そして送信器５０８−５１２を順次又は同時に動作させることにより容易に行われ得る。
【００４４】
識別装置１６０は、２以上の伝送チャネルを含むことにより冗長構成要素ダイバーシティを与える。１個の送信器５０８に結合された幾つかのアンテナを有する代替実現形態（アンテナ構成要素ダイバーシティ）においては、指向性ダイバーシティ及び偏波ダイバーシティが、前述のように容易に行われ得て、そして送信器５１２が省略され得る。構成要素ダイバーシティの更に別の実現形態においては、共通アンテナ（例えば、５１０）は、幾つかの送信器（例えば、５０８及び５１２）に結合され得て、そして他のアンテナ（例えば、５１２）が省略され得る。
【００４５】
リンカ及びモニタの機能は、リンカにおける複雑さとモニタにおける計算能力とがトレード・オフ関係であるよう分割され得る。モニタにおける過剰な計算要求を回避するため、一部の計算タスクは、複数のリンカにより並列（例えば、幾つかの同時リンク）に実行され得る。図６に示されるようなモニタ及びリンカの代表的実現形態においては、モニタ１０６は、制御器６１０、メモリ６１２、及びネットワーク・インターフェース６１４を含み、それぞれは、情報、状態及び制御の交換のため従来のデータ・バス６１６に結合されている。リンカ１１０は、アンテナ選択及び同調回路６４２、スケーリング及び比較回路６４４、及び組み合わせ回路６４６を含む。モニタ１０６及びリンカ１１０は、アナログ及びディジタル回路の任意の通常の混合形式を含む。それら回路の混合形式には、上記で参照した米国特許出願０９／３７２，２７４においてモニタ及びアンテナに対して記載されたタイプの回路で且つ本明細書で説明された機能を実行するよう適切に適合されたものが含まれる。
【００４６】
メモリ６１２は、制御器６１０により実行されるプログラム・ステップと、前述のようにリンカ１１０へバス１０８上を通信されるべき指令に関連した情報と、前述のようにバス１０８を介してホスト・コンピュータ１０２へ通信することに関連した情報とを格納のための従来のＲＡＭ、ＲＯＭ、ＰＲＯＭ及び／又はＥＰＲＯＭを含み得る。
【００４７】
ネットワーク・インターフェース６１４は、制御器６１０とバス１０４との間の従来のバス・インターフェース・プロトコル・サポートを与える。制御器６１０は、Ｉ／Ｏ読み出し及び書き込み指令を、バス６１６を介してネットワーク・インターフェース６１４に与えて、ネットワーク・インターフェース６１４の動作のための初期条件（例えば、ブロック転送開始アドレス及び長さ）を確立し、そして誤り条件に応答し得る。ネットワーク・インターフェース６１４は、メモリ６１２へのホスト・コンピュータ１０２の読み出し及び書き込みアクセスを与え得る。ネットワーク・インターフェース６１４は、ホスト・コンピュータ１０２とメモリ６１２との間の任意の情報及びファイルの転送を容易にする。
【００４８】
任意の数のアンテナ６３９（例えば、２から６の間が好ましい）がリンカ１１０に結合され得る。各アンテナは、アンテナ選択及び同調回路６４２に結合された任意の従来のアンテナ（例えば、ループ、マルコニー、ダイポール、八木、又は皿型）を含み得る。アンテナ選択及び同調回路６４２は、（ａ）アンテナ６３９とスケーリング及び比較回路６４４との間のインピーダンス・マッチング、及び（ｂ）１つ又はそれより多いアンテナ６３９をスケーリング及び比較回路６４４へ選択的に結合することのため制御器６１０からの通常の指令に応答して動作する回路（例えば、リレー又は半導体部品を含む）を含み得る。
【００４９】
スケーリング及び比較回路６４４は、信号６４３をアンテナ選択及び同調回路６４２から受け取る。このスケーリング及び比較回路６４４は、（ａ）それぞれの正規化信号がアンテナ信号の１つ又はそれより多い特性の１つの測定値又は一連の測定値に応答し、且つそれぞれの正規化信号が対応する独立変数のそれぞれの値のしるしを搬送する、所定数の正規化信号を与えるため、及び（ｂ）１つ又はそれより多いリンク・スレッショルドを参照して実行される比較を実行して、各独立変数のためバイナリ結果を与えることのため制御器６１０からの通常の指令に応答して動作する回路（例えば、受信器、復調器、減衰器、増幅器、フィルタ、アナログ比較器、ディジタイザ、及び／又はディジタル比較器を含む）を含み得る。例えば、１ビット・バイナリ結果は、信号の振幅（独立変数の値のしるし）とリンク・スレッショルドを搬送するアナログ信号とのアナログ比較により与えられ得る。複数のビット・バイナリ結果が与えられることになるとき、リンク・スレッショルドは、アナログ／ディジタル変換に対するステップの大きさを指定し得る。
【００５０】
組み合わせ回路６４６は、スケーリング及び比較回路６４４により与えられたバイナリ結果信号６４５を受け取る。組み合わせ回路６４６は、（ａ）処理のため全て又はいずれのサブセットの信号６４５を選択するため、及び（ｂ）１つ又はそれより多い論理的演算を実行して、検出のしるしを有するその結果生じるバイナリ信号を与えるようにそれぞれの独立変数の状態を組み合わせるため制御器６１０からの通常の指令に応答して動作する回路（例えば、論理ゲート、記憶素子、論理演算装置（ＡＬＵ）又はプログラムを格納したマイクロプロセッサ）を含み得る。例えば、組み合わせ回路６４６は、少なくとも１つの識別装置が検出されたことを指示する１ビット・バイナリ信号を与え得る。代替として、組み合わせ回路６４６は、（ａ）１ビット値（例えば、ＴＡＧ＿ＤＥＴＥＣＴＴＥＤ）、（ｂ）検出された識別装置の同一性（ＩＤ）のしるし、（ｃ）衝突が生じたか否かのしるし、（ｄ）識別装置が存在することが期待される位置の範囲（例えば、モニタからの距離の範囲、リンカからの距離の範囲、又はアンテナ又はアンテナ・クラスタのような参照点からの距離の範囲）のしるし、及び（ｅ）識別装置へ向かう方向（例えば、モニタ、リンカ、アンテナ又はアンテナ・クラスタのような任意の通常の参照点から参照される立体角の範囲）のしるしを備える１つ又はそれより多いバイナリ結果をバス１０８上へ与え得る。
【００５１】
組み合わせ回路は、表２に記載される論理的関係のうちの１つ又はそれより多い関係を採用し得る。表２において、独立変数は、大文字のＡからＨにより示されている。各独立変数は、図１に示されるようなリンクに対応し得る。例えば、変数Ａ，Ｂ，Ｃ，Ｄ，Ｅ，Ｆ，Ｇ，Ｈ及びＫは、リンク１５１，１５２，１５３，１５４，１５５，１５６，１５７，１５８及び１５９にそれぞれ対応し得る。本発明の様々な局面に従った別の実現形態においては、変数は、同じリンクの経路に対応し得る。例えば、変数Ｃ，Ｄ及びＥは、図２の点２１８で終了する複数の経路、即ち２３０，２３４，２３８に対応し得る。別の例として、識別装置１６０は、リンカ１１０の２つのアンテナ（各々のアンテナは異なるアンテナ・パターンを有する）に（例えば、反射のため）到達する信号を１つのアンテナから送信し得る。これらのアンテナの各アンテナ上の信号に応答して、２つの独立変数は、それぞれの被受信信号の特性（例えば、振幅）に対応する値を割り当てられ得る。更に別の例として、独立変数の値は、同じ識別装置から（最小数の送信及び受信チャネルから）であるがしかし前述したように時間のダイバーシティで得られることができる。
【００５２】
【表３】

【００５３】
【表４】

【００５４】
モニタ１０６及びリンカ１１０は、前述のダイバーシティの任意の組み合わせを与えるよう協働し得る。識別装置の増分的コストが何千の識別装置及び僅かしかないモニタ及びリンカを有するシステムにおいてシステムのコストを支配する傾向があるので、指向性ダイバーシティ、信号の大きさダイバーシティ、信号偏波ダイバーシティ、信号タイミング・ダイバーシティ、信号変調ダイバーシティ、及び／又は冗長構成要素ダイバーシティを主としてリンカ及び／又はモニタで実行することが好ましい。例えば、複数のアンテナ、複数の受信器回路、及び／又は複数の復調回路は、図５及び図６を参照してある程度説明されたビーコン・タイプの識別装置検出システムに対して前述したようにリンカ１１０において実施され得る。
【００５５】
制御器６１０は、リンクを維持するため閉ループ制御システムを実行するための回路及び／又はソフトウエアを含み得る。例えば、期待された識別装置がもはや検出されないとき、制御器６１０は、次の動作、即ち、（ａ）１つ又はそれより多い異なるアンテナ・パターンの使用を指定すること（例えば、送信器出力パワー、受信器感度、アンテナ選択、又は信号を用いた同調回路６４２に対する同調を適切に指図又は調整することによる）、（ｂ）異なるスケーリング及び比較機能の使用を指定すること（例えば、回路６１４を適切に指図及び／又は調整することによる）、及び（ｃ）異なる組み合わせ演算を指定すること（組み合わせ回路６４６を適切に指図及び／又は調整することによる、又は例えば、方法７００及びステップ７０８を参照して以下で説明されるように、検出の異なる方法を用いることによる）のうちのいずれかを実行するためのステップを取り得る。一旦、期待された識別装置が再び検出されると、更なるリンク維持動作が取られて、例えば、ヒステリシスを生じさせるためタイマ又は値（例えば、下側又は上側の限界）を設定することにより追加のシステム安定性を与え得る。期待された識別装置の検出の信頼性がより少なくなるとき、対象物識別システム１００は、警告表示、メッセージ又は警報を与え得る。
【００５６】
識別装置が検出されたか否かを決定するための本発明の様々な局面に従った方法は、次のステップ、即ち、（ａ）媒体ダイバーシティ、指向性ダイバーシティ、信号の大きさダイバーシティ、信号偏波ダイバーシティ、信号タイミング・ダイバーシティ、信号変調ダイバーシティ、及び冗長構成要素ダイバーシティから成る組のうちの１つのダイバーシティを有するシステムにおいて、回路が少なくとも２つの独立変数のしるしを与えるのを可能にするステップ、（ｂ）各独立変数に対してバイナリ結果を決定するステップ、（ｃ）複数の所定の方法から論理的組み合わせを形成するための方法を選択するステップ、及び（ｄ）識別装置が上記方法の実行に従って検出されたことを決定して、上記複数のバイナリ結果に従って論理的組み合わせを形成するステップを含み得る。
【００５７】
図７の方法７００は、アンテナのダイバーシティ及びアンテナ・パターンのダイバーシティ（例えば、指向性ダイバーシティ、信号偏波ダイバーシティ及び冗長構成要素ダイバーシティの組み合わせ）を有するシステムに適用されたそのような方法の一例である。方法７００を実行するための命令は、メモリ６１２に格納され、そして制御器６１０により実行され得る。方法７００を実行することにより、ホスト・コンピュータ１０２は、範囲内にある識別装置の検出の最新の報告を周期的に受け取り得る。範囲内の条件を定義するための判定基準は、最初に設定され、又は変化の影響下にある（例えば、オペレータの制御に応答する、所望の識別装置を物理的に配置するための方法に応答する、及び／又は設置又は施設内の物理的変化に応答する）。１組の判定基準が確立されてしまうとき、設置特有の感度及び正確さの判定基準が、例えば、メモリ６１２から同じもののしるし（例えば、そこにオペレータとの対話の結果として、又はホスト・コンピュータ１０２により格納されているように）読み出すことにより決定され得る（ステップ７０２）。
【００５８】
これらの判定基準を取得することに応答して、ある一定数の使用可能なアンテナのそれぞれの特性が決定される（ステップ７０４）。アンテナ特性は、事前に決定され、そしてホスト・コンピュータ１０２によりメモリ６１２に格納され得る。代替として、リンカ１１０（又は、ホスト、モニタ、及び／又はリンカが協働して）は、アンテナ特性をその位置で最初に又は周期的に決定し、そして結果をメモリ６１２に格納し得る。リンカ１１０は、アンテナ特性（例えば、アンテナ同調にも用いられる。）を試験し且つ格納するためプロセッサ（図示せず）及びメモリ（図示せず）のそれぞれを含み得る。リンカのメモリの関連内容にアクセスすること又はそれを転送することは、アンテナ特性を決定する制御器６１０に対して事前に必要不可欠であり得る。
【００５９】
識別装置検出のため用いられるべきアンテナの数が次ぎに確立される（ステップ７０６）。例えば、用いられるべきアンテナは、前述のように、スケーリング及び比較回路６４４に選択的に結合され得る。代替として、用いられるべきでないアンテナは、（例えば、アンテナ信号をスケルチングすることにより、又は信号を重畳して、アンテナ信号が組み合わせのため用いられるべきでないことを指示することにより）無効のままにされ得る。
【００６０】
複数の受信チャネルの構成は、従来のディジタル制御技術により達成され得る。ＲＦ及び／又はアナログ・スイッチを制御する出力を有するレジスタは、制御器６１０からの指令により設定され得る（ステップ７０６）。アンテナを、適切な受信周波数に自動的に同調することは、メモリ６１２に格納されている表からの情報を、アンテナ選択のためのマトリックス・スイッチを動作させるレジスタに類似のレジスタに転送することにより達成され得る。他のパラメータは、スケーリング（例えば、ラダー、プログラム可能増幅器）、アナログ比較のためのアナログ・スレッショルドを（例えば、ラダー及び／又はＤ／Ａ変換器により）設定し、及びディジタル比較のためディジタル・スレッショルドを設定する（例えば、レジスタ）ためのディジタルに制御されたスケーリング及び比較回路６４４に対して類似の要領で設定され得る。パラメータの設定のタスクは、ステップ７０６で全部（例えば、初期化として）達成され、又は、以下で説明されるステップ７１０である程度示されるように、検出全体にわたって反復され得る。
【００６１】
識別装置検出を決定するため用いられるべき論理式（例えば、表２を参照して前述したような）が、メモリ６１２に、変数に対する論理演算子及び参照を含むメタコードとして格納され得る。そのようなメタコードは、任意の通常の要領でフォーマット化されそして解釈され得る。メタコードとして格納することは、ユーザに対するシステム操作の記述を容易にし、又は修正及び維持を容易にし得る。好適な実施形態において、識別装置検出のための１つ又はそれより多い論理式の実行は直接的であり、即ち、その論理式の論理が実行可能な命令（例えば、コンパイルすること及びアセンブリから得られるオブジェクト・コード）により実行される。そのように、論理式は、比較する及び／又は組み合わせる方法のサブパート（副部分）として実行されるべきサブルーチンとしてメモリ６１２に存在する。任意の従来の技術を用いて、所望のサブルーチンの実行を可能にし得る（ステップ７０８）。例えば、ポインタに所望の値が与えられ（又は所望の値へリンクされ）得て、又はケース・スイッチがスイッチ値を用いて初期化され得て、あるいはメッセージが特定のプログラム・オブジェクトを初期化するため送られ得る。
【００６２】
ステップ７０８で選択された比較する及び／又は組み合わせる方法により参照された各変数に対して現在値を確立するため、ステップ７０６で設定されたパラメータのセッティングとは異なるパラメータのセッティングが適切であろう。例えば、異なるパターンを有する２つのアンテナが「Ａ ＯＲ Ｂ」のような論理式に対する２つのそれぞれの独立変数に対して２つの値を供給するため使用可能にされる場合、ステップ７０６におけるセッティングは十分であり得るし、そしてステップ７１０は省略され得る。他方、例えば、独立変数に対して１個のそのような値を獲得するため、統合化受信器が帯域にわたり掃引されねばならない、又はアンテナが角度にわたり掃引されねばならないとき、同調、スケーリング、及びスレッショルドの比較の決定（ステップ７１０）は、検出における各試みのため必要とされ得る。更に別の実施形態においては、ステップ７１２は、比較する及び／又は組み合わせる選択された方法に全ての変数に対する値が供給されてしまうまで反復される。
【００６３】
前述のように変数の値を供給された１つ又はそれより多い論理式の評価は、本発明の様々な局面に従って、比較する及び／又は組み合わせる方法を実行することにより達成される（ステップ７１４）。そのような方法は、予め決定され得て、又は選択され得て（ステップ７０８）、あるいは一部の変数に関して一部予め決定され、そして他の変数に関して選択され得る。より速い実行は、比較する及び組み合わせる方法の一部又は全てを所定の方法として確立することから結果として生じ得る。
【００６４】
表２を参照して前述した各論理式は、１ビット・バイナリ値を与える。選択されたアンテナから受信された信号に従って得られた他の情報と組み合って、そのような１ビット値は、特定の識別（ＩＤ）を備える識別装置が検出されたか否かを意味する。検出の報告が、ホスト・コンピュータ１０２に与えられ得る（ステップ７１４）。そのような報告は、ホスト・コンピュータ１０２により独立にアクセスされ得るメモリ６１２の領域において通常のメッセージ、ファイル又はしるしのような任意の都合良い形式を取り得る。報告は、代替として又はその上に、２以上の識別装置が誤りなく検出されたこと、又は衝突が生じたことを指示し得る。
【００６５】
方法７００の幾つかのステップは、（ａ）範囲内にあり得る識別装置の母集団（ｐｏｐｕｌａｔｉｏｎ）の変化、又は（ｂ）範囲内の程度（範囲）を定義するパラメータにおける変化の監視及び検出を反復するループの中に組織化され得る。例えば、報告した（ステップ７１４）後に、制御は、（ａ）前述のように、識別装置の検出に用いられるダイバーシティのタイプの変化又は設置情報の変化のため試験（又はその変化を実現）するため始め（ステップ７０２）に、（ｂ）アンテナ、及び／又はパラメータのセッティングのための代替の選択（ステップ７０６）に、（ｃ）比較する及び／又は組み合わせる代替方法の選択（ステップ７０８）に、又は（ｄ）同調、スケーリング、及び／又は比較セッティングのための代替を決定する（ステップ７１０）に戻るよう進み得る。
【００６６】
上記の記載は本発明の好適な実施形態を説明しているが、その好適な実施形態は特許請求の範囲に定義されるような本発明の範囲から逸脱することなく変更又は修正され得る。記載の明瞭のため本発明の幾つかの特定の実施形態が記載されたが、本発明の範囲は、特許請求の範囲により判定されることを意図するものである。
【図面の簡単な説明】
【図１】 図１は、本発明の様々な局面に従った対象物識別システムの機能ブロック図である。
【図２】 図２は、図１の対象物識別システムの一部の代表的設置を含む設備の床配置図である。
【図３】 図３は、範囲内識別装置及び非範囲内識別装置の代表的位置の図である。
【図４】 図４は、本発明の様々な局面に従った識別装置を有する輸送用容器の斜視図である。
【図５】 図５は、本発明の様々な局面に従った識別装置の機能ブロック図である。
【図６】 図６は、図１の対象物識別システムの一部の機能ブロック図である。
【図７】 図７は、本発明の様々な局面に従った方法のフロー・チャートである。
【図８】 図８は、識別装置を検出する確率の、それを超えて通信リンクが延長する距離の関数としてのグラフである。[0001]
[Field of the Invention]
Embodiments of the present invention are of a type of object identification system having a plurality of transmitting and receiving devices sharing a common communication medium, and particularly when the communication suffers reception of a plurality of signals on a plurality of paths. It relates to a method for establishing communication in the presence of a large number of such devices.
[0002]
[Background of the invention]
Conventional data communication systems have been applied to achieve object identification using wireless broadcast media. Such radio frequency identification (RFID) systems have found application in the areas of material handling, inventory management, and generally in the field of personnel, object and animal tracking. The identification devices are of three known types: beacon type passive or active identification devices and transceiver type active identification devices. In a typical configuration, the system may include an interrogator (or system receiver for beacons) and thousands of identification devices. Each identification device is typically packaged as a low cost or disposable label or tag and placed on an object, animal or human being to be tracked. Each identification device is manufactured using integrated circuit technology, programmed with a unique identifier, and assembled with a printed circuit antenna to form a flat assembly for incorporation into a label or tag. Typically, the interrogator (or system receiver) has a fixed position, while the identification device moves in and out of the communication range of the interrogator (or system receiver) from time to time. It is highly desirable to identify the identification device accurately and quickly from a population that can be enormous. At the same time, it is highly desirable to reduce the cost of each identification device.
[0003]
Accurate and reliable detection of the identification device can, for example, (a) have a limited amount of power available to operate when the identification device is required to provide wireless transmission, (b) the identification device The antenna orientation of the device may be inadequate to absorb enough power from the signal transmitted to it, and (c) the antenna orientation of the identification device is received correctly by the interrogator (or system receiver). (D) multiple signals interrogated based on the same transmission by the identification device due to, among other things, reflections of radio frequencies in the environment Can be made difficult by a number of factors, including the fact that the receiver (or system receiver) may arrive, and (e) the identification device transmitting at the same time may cause a so-called collision.
[0004]
Object identification system suitable for harmonizing the use of a common medium among potentially huge numbers (billions) of identification devices for detection, interrogation and / or control activities to be achieved in a limited time There is still a need for. In addition, in some applications, minimizing the circuit, firmware and software complexity required by each identification device, extending the operating range of communications, and possibly interrogators (or system receivers) There is still a need to support a very large number of individual identification numbers at the expense of complexity. Without these improvements, reduce the size and cost per identification device and employ inexpensive and disposable identification devices such as identification tags, trunk tags, inventory labels, and the like. A new and improved object identification system cannot be enabled.
[0005]
[Summary of Invention]
According to various aspects of the present invention, a method for determining whether an identification device has been detected comprises: (a) selecting a plurality of different antenna patterns from a predetermined plurality of antenna patterns; and (b) Determining a plurality of binary results; (c) selecting a technique for forming a logical combination from a plurality of predetermined techniques; and (d) detecting a radio frequency identification device according to performing the technique. And forming a logical combination according to the plurality of binary results. Each binary result is responsive to whether the respective communication link provides a respective signal having a respective amplitude that exceeds a respective threshold. Each communication link operates according to at least one of the selected antenna patterns.
[0006]
By selecting several antenna patterns, each contributing to the respective binary result, a logical combination of binary results is obtained by identifying devices (within range) within the range of one or more selected antennas. A higher probability of detecting (in-range identification devices) and / or identification devices that are not within the range of one or more selected antennas (not-in-range identification devices). Detection can be given with a lower probability of detection. Thus, among other things, more accurate and more reliable detection of the identification device can be obtained, and a faster determination of the identification device of the unknown population can be obtained.
[0007]
In an object identification system according to various aspects of the present invention, power may be provided to an identification device via a transmitted signal using a communication link utilizing one of the selected antennas. By using an antenna selected for this function, the probability of in-range identification devices that absorb sufficient power from the transmitted signal increases and / or non-in-range identification that absorbs sufficient power from the transmitted signal. The probability of the device is reduced. Further, a communication link utilizing one of the selected antennas can be used for communication with the identification device by transmitting to, receiving from, or both transmitting and receiving. By using selected methods that combine binary results determined from the use of one or more selected antennas and / or the use of one or more of the selected antennas, there is no error Increases the probability of communicating with the in-range identification device and / or reduces the probability of communicating with the non-range identification device without error. Supplying power and / or communicating without error may be performed less dependent on the orientation of the in-range identification device antenna. Thus, more accurate and more reliable detection of the identification device is obtained, and initially communication with an unknown number of identification devices takes less time. A less expensive identification device may be utilized when costing from multiple or omnidirectional antenna structures on the identification device.
[0008]
Since multiple signal paths can be useful in an environment that links identification devices with multiple selected antennas, two or more links can be used to power the identification device and / or communicate with the identification device. By combining the respective binary results associated with each reflected radio frequency signal, a more accurate and more reliable detection of the identification device is obtained, and communication with a number of identification devices not initially known is more It takes less time.
[0009]
Two or more links can be used to power the identification device and / or communicate with the identification device, since multiple identification devices can transmit at the same time and can be useful in an environment where so-called collisions can occur. By selecting an antenna for feeding or communication, a subset of identification devices can be enabled to transmit. The probability of collision can be reduced, and more accurate and more reliable communication with a number of identification devices not initially known takes less time.
Embodiments of the present invention will now be further described with reference to the drawings. Wherein, similar names indicate similar components.
[0010]
[Detailed Description of Preferred Embodiments]
An object identification system according to various aspects of the present invention provides communication between a monitor and an object while the monitor and the object are within communication range. Each object may include, for example, a radio frequency identification (RFID) device having an antenna used for communication. As used herein, communication is used to (a) detect the presence of an identification device (e.g., locate an object within a zone); (b) identify operational power. Providing the device, (c) determining the identity of the identification device, (e) receiving data from the identification device, or (f) sending the data to one or more identification devices. One or more objectives may be achieved. The transmitted power level may vary according to a range suitable for communication. For example, the object may be detected at a relatively lower transmitted power level to avoid collisions as described above. Communications can be modulated for the same or different media, frequency, or different purposes (eg, magnetic induction, wireless using amplitude modulation, frequency shift keying modulation, or pulse code modulation, to name a few representative options) , Infrared light, or sound). Different media, frequencies, or modulations can be used simultaneously or at different times for the same purpose. In accordance with various aspects of the present invention, communication is established and changes in the orientation of each object antenna, changes in coupling between object antennas, and changes in discontinuities along the communication path (eg, reflection, absorption or refraction). To overcome the aforementioned problems including proximity of object antennas to surfaces that can interfere with communications. For example, the object identification system 100 may include a host computer 102, networks 104 and 108, monitors 106 (representing any number of monitors coupled to the networks 104 and 108), linkers 110, 112, 114. , 116 (representing any number of linkers coupled to network 108), and identification devices 160, 170, and 180 (representing any number and orientation of in-range identification devices).
[0011]
Host computer 102 may include any computer system having computing capabilities and interfaces to support data communication over network 104 between one or more monitors 106-107. A normal office computer system may be used. The host computer 102 receives notifications for objects detected or identified by one or more monitors 106-107 and performs any different normal business processes in response to such notifications. Can act to do. Typically, host computers provide inventory accounting, point-of-sale (POS) services, material handling, automated data collection, electronic article monitoring, or electronic access control in response to objectification detection or identification The object may then include an employee badge, identification tag, shipping tag, inventory label, electronic key, authorization device, or price tag.
[0012]
Network 104 may include any network for data transfer between a monitor and a host computer (eg, the Internet using cable, telephone or wireless technology, wide area network, local area network). Moreover, the network 104 may support data transfer between one or more monitors 106-107. Processing tasks between any normal network protocol, eg, monitors operating in parallel (eg, independently or redundantly) or working together (eg, sharing control information or computed results) Protocols that include messages for assigning can be used.
[0013]
The network 108 can be any network for transferring data between linkers and monitors, or between linkers (eg, the Internet using cable, telephone or wireless technology, wide area network, local area network). May be included. Any normal network protocol, eg, processing tasks between linkers operating in parallel (eg, independently or redundantly) or working together (eg, sharing control information or computed results) Protocols that include messages for assigning can be used. The networks 104 and 108 can be logically separated (eg, the monitor 106 can act as a regular firewall) or they can be logically or physically integrated.
[0014]
In an alternative implementation, the monitor 106 and the network 104 are removed and the host computer coupled to the network 108 has all the functions described above for the host computer 102 and all the functions described below for the monitor. Execute. In the object identification system 100 as shown, the monitors 106-107 inter alia reduce data volume (data volume) and respond to messages on a network coupled to a host computer (ie, network 104). It works to increase the time available to respond.
[0015]
Monitors 106-107 may receive commands from host computer 102 and provide reports to host computer 102 over network 104. The commands may be the state of any linker 110-116, the state of any monitor (eg, for monitor 106 with respect to itself or with respect to another monitor 107 cooperating with monitor 106), network 104 Or a request by the host computer 102 for the state of the network 108. Commands from the host computer 102 instruct the monitor 106 to select and configure the link to be used for communication with the identification device. In addition, the host computer 102 may request notification of detected objects or a list of object identifications currently within communication range of any monitor (or group of monitors cooperating), as appropriate. Can do. Finally, the host computer 102 may direct the cooperation of the monitor to perform any of the aforementioned functions using appropriate instructions to the monitors 106-107. For example, the monitor may assume the role of the host indefinitely or for a temporary period. The host computer 102 may be omitted, for example, when the monitor performs the functions of the host as described above.
[0016]
The monitor includes any subsystem that communicates with one or more objects and provides the results of such communication. The monitor may include communication and / or computing capabilities. The monitor may communicate at one or more levels of the protocol (eg, calculations associated with wireless signal decoding / coding, message disassembly / assembly, and / or detection / query methods). For example, the monitor may include a wireless receiver as described above. In another implementation, the monitor includes both a wireless transmitter and a wireless receiver (eg, for use with a transponder). In yet another implementation, the monitor does not transmit or receive in a common medium for the identification device, but controls other subsystems that do so (eg, linkers 110-116). In such cases, the monitor does not operate directly on the radio signal and receives a message (eg, a message to or from the subsystem, a message to or from the identification device, and / or a message to or from the host). And software and / or circuitry that responds to the message.
[0017]
The results of identification device detection may be provided to the operator on a monitor (eg, when the host computer 102 is omitted) or to a host computer for processing as described above. Object identification system 100 may include one or more monitors, some of which exceed the capacity of a single monitor due to redundancy or physical distribution of objects. Used when, or perhaps exceeding the expected number of objects in a limited time. For example, the monitors 106-107 are functionally equivalent and can be configured in several zones (eg, geographic regions). Zones can overlap geographically when, for example, each zone uses a different communication medium, frequency, modulation, protocol, or address group. The location of the object within a particular zone may be verified by communication with one or more monitors 106-107. The movement of an object from one zone to another can be determined by the host computer 102 by conventional comparison techniques based on appropriate reports from the monitors 106-107.
[0018]
The linker includes any device that provides a physical interface to a common medium (or common media) used for communication with the identification device. For identification devices that communicate using radio frequencies, the linker includes one or more antennas. The linker can operate independently or with a group of linkers. Thus, one antenna or multiple antennas coupled to one linker can constitute an antenna system or of an antenna system that includes multiple antennas coupled to one or more other antennas. Can be part. An antenna system includes any system for receiving or sending a message between a monitor and one or more objects using one or more antennas. For example, the antenna system 120 is coupled to the monitors 106-107 via the bus 108 and further includes a linker 110 (having antennas 122 and 124), a linker 112 (having antennas 132, 134, 136), a linker. 114 (having antennas 142 and 144) and linker 116 (having antennas 146 and 148). When communication from one or more of several linkers is limited to providing operating power, receive antenna functionality for those linkers and antenna subsystems may be excluded.
[0019]
As shown, an antenna represents any transducer of energy used for communication, including, for example, a lens for infrared light energy, or a horn or structure for acoustic energy. An alternative antenna system includes one or more modules (eg, replaceable components) for reconfiguring operation from any communication medium or frequency band to another medium or frequency band.
[0020]
In implementations having a monitor that includes a wireless receiver and / or transmitter circuit, the linker can select an antenna, perform antenna squelch, antenna impedance matching (eg, perform tuning), receive signal processing ( Analog detector, demodulator, preamplifier, analog / digital converter, and / or pulse counter or timing analyzer circuit), transmit signal pre-processing (eg, gated oscillator, code converter, Digital / analog converters, digital / pulse converters, amplifiers, modulators, message header generators, synchronization signal generators, and message trailer generators), and error detection (eg, CRC generators and / or checkers) For example). When the monitor does not include radio circuitry, the linker may further include one or more receivers and / or one or more transmitters. In any case, the linker accepts commands from the bus 108, provides control signals to the aforementioned circuits, and cooperates with such circuits to perform the method for accomplishing the aforementioned functions, and the status, data And a processor for providing error messages.
[0021]
Detecting the identification device to provide an indication of detection at the host computer 102 (or at one or more monitors 106-107 or at one or more linkers 110-116) With one or more antennas. For example, communications that provide an indication of detection of the identification device 160 are illustrated by links 151 and 152, links 153, 154 and 155 to the object 170 and links 156, 157, 158 and 159 to the object 180. Has been. Each link may include any number of signals in any direction between the antenna and the identification device. For example, the link can be found in James L., incorporated herein. May represent any one or more signals of the type transmitted or received by the object identification system described in US patent application 09 / 372,274 filed August 11, 1999 by Rodgers et al. . It is not necessary for the same antenna node to operate to send and receive communications to a particular identification device. For example, antenna 122 may provide a power signal to identification device 160 on link 151 and antenna 124 may receive a beacon signal provided by identification device 160.
[0022]
Each identification device may have one or more antennas. As described above, the orientation of the identification device antenna includes the orientation of the identification device antenna with respect to the antenna used by the linker to communicate with the identification device, and the orientation of the identification device antenna with respect to the other identification device antennas. including. When essentially a planar antenna is used in the identification device, the coupling of the antenna for power transfer from the linker to the identification device is mainly due to the magnetic field. Such coupling may be reduced because the orientation of the identification device antenna differs from the same plane (or parallel plane) with respect to the linker antenna and other nearby identification device antennas. When the planar antennas are coplanar (or parallel planes) with respect to each other, the identification device receives power from the identification device and a combination of multiple resonant circuits (eg, each identification device is formed with an antenna or an antenna Having a resonant circuit coupled to a) can affect the behavior of one or more such resonant circuits. For example, when each discriminator has one resonant circuit having one resonant frequency when operated separately, a group of discriminators is referred to herein as a different (eg, lower) resonant frequency. ) It may have a peak of energy absorption at frequency. Some identification devices in the stack are not coupled to the same extent as other (eg, the majority) identification devices, and thus are energetic at frequencies between the resonant frequency that is in isolation and the majority of the stack resonance frequencies. Can be absorbed more efficiently. In other words, a non-uniform stack of identification devices can exhibit several stack resonance frequencies.
[0023]
In general, a link as described above includes signals transmitted by a transmitter and received by a receiver (or power circuit). The link may include either in-range identification devices or non-in-range identification devices. Whether the link includes an in-range identification device depends on the antenna pattern of the transmitter, the antenna pattern of the receiver, the distance traveled by the RF energy associated with the signal, the characteristics of the medium through which the energy passes, and the energy absorption Depends on factors including environmental properties that contribute to reflection and refraction. One or more factors may change over time during the duration of communication over the link. One or more factors may vary in time during the duration of communication over the link. An antenna pattern is a spatial (eg, two-dimensional or three-dimensional) representation of the performance of an antenna (or array of antennas). The antenna pattern for the transmit antenna describes the radiated field strength measured (or predicted) at various points. An antenna pattern for a receive antenna may describe the minimum electromagnetic field strength at various points that would provide a defined electrical signal at the antenna.
[0024]
Communication over a link may include several such signals of various durations that overlap or separate in time. Each signal when the identification device detection includes several signals (eg, power, ringing, response, query, further response, etc.) due to, for example, system architecture, protocol, and reliability criteria Individually and each combination of one or more such signals contributes to whether the identification device is in range or out of range (out of range). Multidimensional definitions within this range can be better understood by closer consideration of the simpler case in one dimension, ie, link distance.
[0025]
As an ideal goal, the probability of detecting all in-range discriminators should be 100%, and the probability of detecting non-in-range discriminators as in-range should be 0%. This ideal is illustrated in FIG. 8, where the range is simply defined with reference to a single variable, the link distance defined as the distance between communication devices (eg, linker and identification device). Yes. As shown, the identification device is in range when the link distance is less than the distance D14. The probability of detection (curve 802) is 100% for all link distances that are less than or equal to distance D14. Beyond the distance D14, the detection probability is 0%. Since that ideal is not feasible for a number of reasons (eg, changes in antenna coupling, noise floor, and others mentioned above), the real probability is with distance as shown by curve 806. change. For example, the probability of detecting the identification device at the distance D12 is not certain, and the probability P18 corresponding to D12 in the curve 806 is less than 100% (eg, 80%).
[0026]
When the probability is not 100%, two types of errors can exist in any proportion. Initially, identification devices that are out of range may be detected (so-called false positive detection). Secondly, identification devices that are in range cannot be detected (so-called failure or incomplete detection). Incomplete detection can dominate the actual error at distance D12, and false positive detection can dominate the actual error at distance D16. At distance D14, the probability of detection of the in-range identification device (P16) may be close to 50%. This link distance is referred to herein as the threshold link distance.
[0027]
In accordance with various aspects of the present invention, the threshold link distance (ie, the detection of all in-range identification devices at that distance is approximately 50%) can be adjusted. Any conventional mechanism for adjusting link reliability may be used for adjustment. The optional conventional mechanism includes a link transmitter or receiver to adjust the amount of energy transmitted (eg, for a link used to transmit power to an identification device or an interrogation signal to the identification device). To adjust the amount of antenna coupling (eg, to reduce any mismatch including orientation, electronics vs. physical antenna, or antennas relative to each other via mediation) and / or adjust receiver sensitivity Circuitry and / or software is included. For example, within a range that is simply defined by the link distance, where the probabilities are equal in all physical directions (eg, a completely omni-directional antenna is used for the transmitter and receiver of the link). Again, the in-range identification device can be considered to be within a planar circular contour 304 as shown in FIG. The identification device 310 can be considered within range (eg, corresponding to the distance D12 in FIG. 8) and the identification device 314 is out of range (eg, corresponding to the distance D16 in FIG. 8). Can be considered. Identification devices 312 and 316 may represent a device that happens to be at distance D14, or identification devices 312 and 316 may be arranged to delimit contour 304 in accordance with various aspects of the invention.
[0028]
For example, one or more discriminators can be known to exist (regardless of the shape of the contour) on any desired contour, and the threshold link in the direction of the known discriminator The distance may be adjusted in a series of tests to give a predetermined target probability of detection (eg, 50% or more than 50% for safety margin) through several sample readings. The use of hardware and / or software settings (eg, transmitter power, antenna orientation, receiver sensitivity, etc. as described above) that gave the desired link distance during such testing is then tested. Or can be used to determine appropriate settings for other directions and / or other link distances (according to the link distance model in the environment).
[0029]
The first group setting corresponding to the first link distance is used in conjunction with the second group setting corresponding to incrementally longer link distances, at which physical distance a particular identification device is present. Can help find out. For example, since the identification device 314 responds with less than 50% of the time due to the first group setting and more than 50% of the time due to the second group setting, the identification device 314 corresponds to both circular contours 304 and 318. Can be determined to exist between the link distance radii.
[0030]
In accordance with various aspects of the present invention, the presence of multiple paths for a link can be used to establish system performance closer to the ideal curve 802, eg, curve 804. A system operating according to curve 804 will exhibit a lower probability of false positives and a lower probability of incomplete detection. A system according to various aspects of the present invention operates on a curve, such as curve 804, in an environment where the link has multiple paths. As shown in FIG. 3, each link 302, 306, and 308 includes exactly one segment (part of a line) between the ends of the links (eg, 300 and 310 for path 302). However, in practice, irregularities in the medium can cause multiple physical communication paths for a link. The media in the facility can be bounded by reflective or absorbing surfaces. For example, the facility 200 of FIG. 2 includes walls 202 and 204 connected at right-angle corners, walls 206 and 208 connected at the corners of 225 degrees and forming a passage between the walls 204 and 206, and generally It includes a wall 210 that faces the aforementioned wall. The link between points 216 and 218 has three paths: (a) segment 234 providing reflection from segment 232 and wall 202, (b) segment 238 providing reflection from segment 236 and wall 208, and (c ) May include segments 230 that arrive without reflection. These three paths have different effective link distances (eg, the sum of the segments on each path corresponds to one effective link distance).
[0031]
The planar contour 220 of FIG. 2 with a long dashed line illustrates the trajectory of a point with a 50% probability of detection by the identification device. As represented by the RF link, the antenna at point 216 is not omnidirectional, so the contour 220 (instead of having a circular shape centered at point 216) extends generally toward wall 208. Has a tear shape. In other words, the planar contour 220 represents a part of the antenna pattern. The first portion of the tip of the pattern 220 is reflected from the wall 208 as indicated by the dash-dot line 222. The second portion of the tip of the pattern 220 is reflected from the wall 202 toward the wall 210 as indicated by the short dashed line 224. A portion of the tip of the pattern 220 reflects from the wall 202 and then from the wall 210 as indicated by the + symbol line 226. Paths 232 and 234 are in range and correspond to the first reflection in dashed line 224. Paths 236 and 238 are in range and correspond to the first reflection in the dash-dot line 222. And all points of the second reflection within the + symbol line 226 are out of range.
[0032]
Of course, the determination within the range referring to the link distance is not limited to the reference of the contour in the plane. For example, the trajectory of a three-dimensional point is determined by analysis or testing so that all such points are regular surfaces (eg, spheres or toroids) or irregular surfaces (eg, various lobe volumes). It may present a probability that is consistent with a model for defining within a range that is part of a multi-lobe surface) having a volume). Since the antenna (and reflected RF energy) presents a pattern that can be directional, polarizable, or a combination of directional and various polarities, link to the first antenna A determination within a range with reference to distance (eg, horizontally polarized) is substantially independent of a determination with reference to a link distance to the second antenna (eg, vertically polarized). Can be.
[0033]
By operating each link according to the latest mathematical model of the link, the system of the present invention operates more reliably closer to the ideal function of the probability of detection illustrated by the example in FIG. 8, as described above. To do. In other words, by seeking to establish a link according to such a model, one or more characteristics of the established link can be determined (eg, the distance between the transmit and receive antennas). Can be predicted more accurately.) Such a model can be used explicitly or implicitly in a method of communicating with the identification device or locating the identification device. For example, one or more link thresholds can be determined according to a model having a number of variables. Each of these variables is set to a value according to a test (eg, a test as described above with reference to FIG. 3). In order to simplify the test and improve the accuracy of the conclusions drawn from the model, the preferred model contains two or more independent variables. A variable is considered independent when the value of one independent variable does not always correspond to the same value of another independent variable. When a link contains one path at each of two frequencies and a narrowband observation (eg, a test) is made at one end of the link, the resulting measurement can be added to the model as an independent variable value. Table 1 lists the features of the system of the present invention that can produce independent variables.
[0034]
[Table 1]

[0035]
[Table 2]

[0036]
In addition to combining any of the above features to obtain a very large number of independent variables, some of the features can be substituted for others. For example, a rotating directional antenna can be considered directional diversity as well as timing diversity in that communication through the same direction is as good as it can be obtained at periodic times. Diversity can be realized simultaneously or sequentially. As an example of sequential diversity, timing diversity may involve a single transmission multiple reception, or a sequential (eg, periodically repeated) transmit-receive event.
[0037]
Diversity for the purpose of determining the value of the independent variable at the linker end (eg, as determined by the linker 110, monitor 106, and / or host computer 102) for the link between the linker and the identification device. Can be implemented either in the linker or in the identification device. For example, direction and / or polarization diversity may be achieved by one or more identification devices located on the same object to be tracked. For illustrative purposes, the object 400 of FIG. 4 (eg, a normal shipping box) has side surfaces 410, 420, and 430 that are orthogonal to each other, and identifications attached coplanar to the side surfaces 420 and 430, respectively. It includes devices 450 and 452, an identification device 440 co-planarly attached to the two side surfaces 410 and 420, and an identification device 440 co-planarly attached to the three side surfaces 410, 420 and 430. The identification device on the object 400 may respond with the same identification signal characteristic or sign.
[0038]
The identification device may include a type of antenna that is substantially planar and is subject to directivity and / or polarization characteristics. Identification devices 450 and 451, each having this type of antenna, can be used to exhibit direction and / or polarization diversity when mounted on mutually perpendicular surfaces of the object, as shown. The identification device may have more than one antenna of this type. Direction and / or polarization diversity can be obtained by using different orientations for each antenna of the plurality of antenna identification devices. For example, the identification device 440 includes a portion 441 having a first antenna disposed on the side surface 410 of the object 400 and a portion 442 having a second antenna disposed on the side surface 420 of the object 400. . Further, the identification device 444 includes a portion 445 having a first antenna disposed on the side surface 410 of the object 400, a portion 446 having a second antenna disposed on the side surface 420 of the object 400, and the object. And a portion 447 having a third antenna disposed on a side surface 430 of the object 400. The function of the antenna (eg, for power absorption, resonance detection, message reception, and / or message transmission) may be the same or different in such an identification device (440 or 444). When different, antenna functions may participate in the same link or different links.
[0039]
An identification device in accordance with various aspects of the present invention may facilitate media diversity, directional diversity, polarization diversity, signal timing diversity signal, modulation diversity, redundant component diversity, or any combination thereof. For example, the beacon identification device 160 of FIG. 5 includes a battery 502, a controller 504, and several transmission channels. Each transmission channel includes a transmitter (508 and 512) and a respective antenna (510 and 514). The battery 502 supplies power to the controller and transmitter via a conductor 501. The controller 504 determines when any or all transmitters transmit and what signals (eg, content, frequency (s) and / or modulation) each will transmit. To do. Any conventional components, circuits, structures, materials and techniques can be used to fabricate and assemble the identification device 160.
[0040]
The components, circuits, structures, materials, and techniques of identification device 160 for manufacturing are described herein in any conventional type, including the types described in the above referenced US patent application 09 / 372,274. May be suitably adapted to perform the functions described in.
[0041]
Media diversity can be performed by using a transmitter and interface to another medium (eg, a piezoelectric oscillator and a radiating surface for ultrasound signals) instead of any one or more transmission channels.
[0042]
Directional diversity and polarization diversity can be easily performed by employing antennas 510 and 514 with different antenna patterns, as described above.
[0043]
Signal modulation diversity can be easily accomplished by employing different modulations at each transmitter 508-512 and operating transmitters 508-512 sequentially or simultaneously.
[0044]
The identification device 160 provides redundant component diversity by including two or more transmission channels. In an alternative implementation (antenna component diversity) with several antennas coupled to one transmitter 508, directional diversity and polarization diversity can be easily performed as described above and transmitted. The vessel 512 can be omitted. In yet another implementation of component diversity, a common antenna (eg, 510) can be coupled to several transmitters (eg, 508 and 512) and other antennas (eg, 512) are omitted. Can be done.
[0045]
The linker and monitor functions can be partitioned such that the complexity at the linker and the computing power at the monitor are in a trade-off relationship. To avoid excessive computational demands on the monitor, some computational tasks can be performed in parallel (eg, several simultaneous links) by multiple linkers. In the exemplary implementation of the monitor and linker as shown in FIG. 6, the monitor 106 includes a controller 610, a memory 612, and a network interface 614, each of which is conventionally used to exchange information, status, and control. Data bus 616. The linker 110 includes an antenna selection and tuning circuit 642, a scaling and comparison circuit 644, and a combinational circuit 646. Monitor 106 and linker 110 include any conventional mixed form of analog and digital circuitry. The mixed form of those circuits is suitably adapted to perform the functions described herein with a circuit of the type described for monitors and antennas in US patent application 09 / 372,274 referenced above. Included.
[0046]
Memory 612 includes program steps executed by controller 610, information related to commands to be communicated over linker 108 to linker 110 as described above, and host computer via bus 108 as described above. Conventional RAM, ROM, PROM and / or EPROM for storing information related to communicating to 102 may be included.
[0047]
Network interface 614 provides conventional bus interface protocol support between controller 610 and bus 104. Controller 610 provides I / O read and write commands to network interface 614 via bus 616 to provide initial conditions for operation of network interface 614 (eg, block transfer start address and length). Establish and respond to error conditions. Network interface 614 may provide read and write access of host computer 102 to memory 612. Network interface 614 facilitates the transfer of any information and files between host computer 102 and memory 612.
[0048]
Any number of antennas 639 (eg, preferably between 2 and 6) may be coupled to the linker 110. Each antenna may include any conventional antenna coupled to an antenna selection and tuning circuit 642 (eg, loop, Marcony, dipole, Yagi, or dish). Antenna selection and tuning circuit 642 selectively couples (a) impedance matching between antenna 639 and scaling and comparison circuit 644, and (b) one or more antennas 639 to scaling and comparison circuit 644. In order to do so, it may include circuitry (eg, including relays or semiconductor components) that operate in response to normal commands from controller 610.
[0049]
Scaling and comparison circuit 644 receives signal 643 from antenna selection and tuning circuit 642. The scaling and comparison circuit 644 includes: (a) each normalized signal is responsive to a measurement or series of measurements of one or more characteristics of the antenna signal, and each normalized signal corresponds. Carry an indication of each value of the independent variable, provide a predetermined number of normalized signals, and (b) perform comparisons performed with reference to one or more link thresholds, Circuits that operate in response to normal commands from controller 610 to provide binary results for variables (eg, receiver, demodulator, attenuator, amplifier, filter, analog comparator, digitizer, and / or Including a digital comparator). For example, a 1-bit binary result can be given by analog comparison of the signal amplitude (indicator of the value of the independent variable) with an analog signal carrying a link threshold. When multiple bit binary results are to be provided, the link threshold can specify the step size for the analog / digital conversion.
[0050]
The combinational circuit 646 receives the binary result signal 645 provided by the scaling and comparison circuit 644. Combinatorial circuit 646 results in (a) selecting all or any subset of signals 645 for processing, and (b) performing one or more logical operations with detection indications. Stores a circuit (eg, logic gate, storage element, logic unit (ALU) or program) that operates in response to normal commands from controller 610 to combine the states of each independent variable to provide a binary signal A microprocessor). For example, the combinational circuit 646 may provide a 1-bit binary signal that indicates that at least one identification device has been detected. Alternatively, the combinational circuit 646 may indicate (a) a 1-bit value (eg, TAG_DETECTED), (b) an identity (ID) of the detected identification device, (c) an indication of whether a collision has occurred, ( d) in a range of locations where the identification device is expected to be present (eg, a range of distances from a monitor, a range of distances from a linker, or a range of distances from a reference point such as an antenna or antenna cluster) One or more indicia comprising indicia and (e) indicia towards the identification device (eg, a range of solid angles referenced from any normal reference point such as a monitor, linker, antenna or antenna cluster) Many binary results can be provided on the bus 108.
[0051]
The combinational circuit may employ one or more of the logical relationships described in Table 2. In Table 2, independent variables are indicated by capital letters A through H. Each independent variable may correspond to a link as shown in FIG. For example, variables A, B, C, D, E, F, G, H, and K may correspond to links 151, 152, 153, 154, 155, 156, 157, 158, and 159, respectively. In another implementation in accordance with various aspects of the invention, the variables may correspond to the same link path. For example, the variables C, D, and E may correspond to multiple paths that end at point 218 in FIG. 2, namely 230, 234, and 238. As another example, the identification device 160 may transmit signals from two antennas that reach the two antennas of the linker 110 (each antenna has a different antenna pattern) (eg, due to reflection). In response to the signal on each of these antennas, the two independent variables may be assigned values corresponding to the characteristics (eg, amplitude) of the respective received signal. As yet another example, the value of the independent variable can be obtained from the same identifier (from the minimum number of transmit and receive channels) but with time diversity as described above.
[0052]
[Table 3]

[0053]
[Table 4]

[0054]
Monitor 106 and linker 110 may cooperate to provide any combination of the aforementioned diversity. Directive diversity, signal magnitude diversity, signal polarization diversity, signal, because the incremental cost of the identifier tends to dominate the cost of the system in systems with thousands of identifiers and few monitors and linkers Preferably, timing diversity, signal modulation diversity, and / or redundant component diversity is performed primarily at the linker and / or monitor. For example, multiple antennas, multiple receiver circuits, and / or multiple demodulation circuits may be used as described above for the beacon-type discriminator detection system described in part with reference to FIGS. 110 may be implemented.
[0055]
Controller 610 may include circuitry and / or software to implement a closed loop control system to maintain the link. For example, when the expected identification device is no longer detected, the controller 610 may specify the next action: (a) specifying the use of one or more different antenna patterns (eg, transmitter output power (B) specify the use of different scaling and comparison functions (e.g., circuit 614 as appropriate), by appropriately directing or adjusting receiver sensitivity, antenna selection, or tuning to the tuning circuit 642 using signals And (c) specifying different combinational operations (by appropriately directing and / or adjusting combinational circuit 646, or see, for example, method 700 and step 708). For performing any of the above (by using different methods of detection, as described below) It can take. Once the expected identification device is detected again, further link maintenance actions are taken and added, for example, by setting a timer or value (eg, lower or upper limit) to cause hysteresis. Can give the system stability. When the expected identification device detection becomes less reliable, the object identification system 100 may provide a warning indication, message or alarm.
[0056]
The method according to various aspects of the present invention for determining whether an identification device has been detected comprises the following steps: (a) medium diversity, directional diversity, signal magnitude diversity, signal polarization. Enabling a circuit to provide an indication of at least two independent variables in a system having a diversity of one of a set of diversity, signal timing diversity, signal modulation diversity, and redundant component diversity; (b) ) Determining a binary result for each independent variable; (c) selecting a method for forming a logical combination from a plurality of predetermined methods; and (d) an identification device detecting according to the execution of the method. Logical combination according to the above binary results It may comprise the step of forming a.
[0057]
The method 700 of FIG. 7 is an example of such a method applied to a system having antenna diversity and antenna pattern diversity (eg, a combination of directional diversity, signal polarization diversity, and redundant component diversity). . Instructions for performing method 700 may be stored in memory 612 and executed by controller 610. By performing the method 700, the host computer 102 may periodically receive an up-to-date report of detection of identification devices that are in range. Criteria for defining conditions within range are initially set or under the influence of change (e.g. in response to a method for physically positioning the desired identification device in response to operator control) And / or respond to physical changes within the installation or facility). When a set of criteria has been established, the installation-specific sensitivity and accuracy criteria may be, for example, indicia from memory 612 (eg, as a result of operator interaction or host computer 102). (As stored by) can be determined by reading (step 702).
[0058]
In response to obtaining these criteria, the characteristics of each of a certain number of usable antennas are determined (step 704). Antenna characteristics can be determined in advance and stored in memory 612 by host computer 102. Alternatively, the linker 110 (or the host, monitor, and / or linker may work together) may determine the antenna characteristics first or periodically at that location and store the results in the memory 612. The linker 110 may include a processor (not shown) and a memory (not shown) for testing and storing antenna characteristics (eg, also used for antenna tuning). Accessing or transferring the relevant contents of the linker's memory may be essential in advance for the controller 610 that determines the antenna characteristics.
[0059]
The number of antennas to be used for identification device detection is then established (step 706). For example, the antenna to be used can be selectively coupled to the scaling and comparison circuit 644 as described above. Alternatively, an antenna that should not be used is left invalid (eg, by squelching the antenna signal or by superimposing the signal to indicate that the antenna signal should not be used for combination). obtain.
[0060]
Configuration of multiple receive channels can be achieved by conventional digital control techniques. A register having an output to control the RF and / or analog switch may be set by command from controller 610 (step 706). Automatic tuning of the antenna to the appropriate reception frequency is accomplished by transferring information from the table stored in memory 612 to a register similar to the register that operates the matrix switch for antenna selection. Can be achieved. Other parameters include scaling (eg, ladder, programmable amplifier), setting analog threshold for analog comparison (eg, by ladder and / or D / A converter), and digital threshold for digital comparison Can be set in a similar manner for digitally controlled scaling and comparison circuit 644 for setting (eg, register). The task of setting parameters can be accomplished entirely at step 706 (eg, as initialization) or it can be repeated throughout detection, as shown in part at step 710 described below.
[0061]
A logical expression (eg, as described above with reference to Table 2) to be used to determine identification device detection may be stored in memory 612 as a metacode that includes logical operators and references to variables. Such metacodes can be formatted and interpreted in any conventional manner. Storing as metacode may facilitate the description of system operations for the user, or facilitate modification and maintenance. In a preferred embodiment, the execution of one or more logical expressions for identification device detection is straightforward, i.e., the logic of the logical expression is executable (e.g., obtained from compiling and assembly). Executed object code). As such, the logical expressions exist in the memory 612 as subroutines to be executed as subparts of the method of comparing and / or combining. Any conventional technique may be used to allow execution of the desired subroutine (step 708). For example, the pointer can be given a desired value (or linked to the desired value), or a case switch can be initialized with the switch value, or a message can initialize a particular program object. Can be sent for.
[0062]
In order to establish a current value for each variable referenced by the comparing and / or combining method selected in step 708, a parameter setting different from the parameter setting set in step 706 may be appropriate. For example, if two antennas with different patterns are enabled to provide two values for two respective independent variables for a logical expression such as “A OR B”, the setting in step 706 is sufficient And step 710 can be omitted. On the other hand, tuning, scaling, and threshold when, for example, the integrated receiver has to be swept across the band or the antenna has to be swept across the angle to obtain one such value for the independent variable. A comparison decision (step 710) may be required for each attempt at detection. In yet another embodiment, step 712 is repeated until the selected method to compare and / or combine has been supplied with values for all variables.
[0063]
Evaluation of one or more formulas supplied with values of variables as described above is accomplished by performing a method of comparing and / or combining according to various aspects of the invention (step 714). . Such methods can be predetermined or selected (step 708), or can be predetermined in part for some variables and selected for other variables. Faster execution may result from establishing some or all of the comparing and combining methods as a predetermined method.
[0064]
Each logical expression described above with reference to Table 2 gives a 1-bit binary value. In combination with other information obtained according to the signal received from the selected antenna, such a 1-bit value means whether or not an identification device with a specific identification (ID) has been detected. A report of the detection may be provided to the host computer 102 (step 714). Such a report may take any convenient form, such as a normal message, file or indicia in an area of memory 612 that can be accessed independently by the host computer 102. The report may alternatively or additionally indicate that two or more identification devices have been detected without error or that a collision has occurred.
[0065]
Some steps of the method 700 may include monitoring and detecting (a) changes in population of identifiers that may be in range, or (b) changes in parameters that define extent (range) within the range. It can be organized into iterative loops. For example, after reporting (step 714), control (a) to test (or to realize) a change in the type of diversity or installation information used to detect the identification device, as described above. At the beginning (step 702), (b) an alternative selection for antenna and / or parameter setting (step 706), (c) an alternative method to compare and / or combine (step 708), or (D) Proceed to return to determining an alternative for tuning, scaling, and / or comparison settings (step 710).
[0066]
While the above description describes preferred embodiments of the present invention, the preferred embodiments may be altered or modified without departing from the scope of the present invention as defined in the claims. For the purpose of clarity, certain specific embodiments of the invention have been described, but the scope of the invention is intended to be determined by the claims.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of an object identification system in accordance with various aspects of the present invention.
FIG. 2 is a floor layout of the facility including a representative installation of a portion of the object identification system of FIG.
FIG. 3 is a diagram of representative positions of an in-range identification device and a non-range identification device.
FIG. 4 is a perspective view of a shipping container having an identification device in accordance with various aspects of the present invention.
FIG. 5 is a functional block diagram of an identification device in accordance with various aspects of the present invention.
FIG. 6 is a functional block diagram of a part of the object identification system in FIG. 1;
FIG. 7 is a flow chart of a method in accordance with various aspects of the invention.
FIG. 8 is a graph of the probability of detecting an identification device as a function of the distance beyond which a communication link extends.

Claims (11)

In a method of determining whether a radio frequency identification device has been detected,
Selecting a plurality of different antenna patterns from a plurality of predetermined antenna patterns;
Determining a plurality of binary results, each binary result responding to whether each communication link provides a respective signal having a respective amplitude that is above a threshold, each communication link comprising: The determining step operating according to at least one of the selected antenna patterns;
Selecting a method of forming a logical combination from a plurality of predetermined methods;
Determining that a radio frequency identification device is detected according to performing the technique and forming a logical combination according to the plurality of binary results.   The method of claim 1, wherein the first threshold is equal to the second threshold. At least one of the respective communication links is
a. A receiver,
b. An antenna coupled to the receiver,
The method of claim 1, wherein the antenna and receiver cooperate according to the respective antenna pattern. At least one of the respective communication links is
a. A transmitter,
b. An antenna coupled to the transmitter,
The method of claim 1, wherein the antenna and transmitter cooperate according to the respective antenna pattern.   The method of claim 1, wherein each selected antenna pattern has a different polarization.   The method of claim 1, wherein each selected antenna pattern has a maximum effectiveness in a different direction as an antenna.   The method of claim 1, wherein at least one of the predetermined techniques provides a logical combination according to a logical OR of at least two of the plurality of binary results. The method of claim 1, wherein at least one of the predetermined methods provides a logical combination according to a logical product of at least two of the plurality of binary results. R1, R2, R3 and R4 represent four results of the plurality of binary results;
The method of claim 1, wherein at least one of the predetermined approaches provides a logical combination according to a logical expression: (R1 OR R2) AND (R3 OR R4). R1, R2, R3 and R4 represent four results of the plurality of binary results;
The method of claim 1, wherein at least one of the predetermined approaches provides a logical combination according to a logical expression: (R1 AND R2) OR (R3 AND R4).   The method of claim 1, wherein at least one of the predetermined techniques provides a logical combination according to whether a sum of the plurality of binary results exceeds a predetermined amount.

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